Antenna array systems for transmitting/receiving data or other information have been devised in a variety of configurations. Phased array antenna systems require numerous and costly components that contribute to a design complexity that may not be acceptable or appropriate for certain applications. In generating transmitted signals using a phased array antenna system, it is commonplace to create a scanning beam or signal in which the beam or signal changes its direction in predetermined increments in one or both of azimuth and elevation.
A transmitted beam or signal can also be developed using antenna arrays in which the collimating surface is parabolic, cylindrical in one direction or where waveguides are employed, such as the pillbox antenna array. With respect to the pillbox antenna array, it is known to apply radio frequency (rf) energy to the pillbox antenna array by means of relatively large-in-size feed horns. For a particular beam to be generated and applied to the pillbox antenna array, one or more dedicated feed horns are activated to form the particular beam. The same feed horn is not utilized in generating different beams for use by the pillbox antenna array.
Phased array antenna systems and other antenna systems have been used in wide and varied applications including locating them in orbit above the earth's surface. Such antennas are useful in obtaining desired information related to what is present or occurring at an instance in time at a particular geographic location. In that regard, such antenna systems can be designed to scan geographic areas as they orbit about the earth. Ideally, in obtaining such information, in scanning between immediately adjacent geographic locations, it is advantageous that such a scan result in obtaining all desired information from the earth's surface, while avoiding loss of information due to incremental changes in the direction of the transmitted signal from the antenna. Loss of such information is commonly the result of high beam-to-beam cross over loss, which refers to insufficient signal overlap between successively transmitted scanning beams or signals.
When evaluating the placement of an antenna system in orbit, an important factor is the weight or payload associated with such an antenna system. It is highly advantageous to keep the weight as low as feasible. With respect to phased array antenna systems, they tend to be not only relatively expensive, but suffer weight penalties based on high density of electronic components. Consequently, it is much more costly to transport such a payload into orbit.
Based on the need for a highly accurate and less costly antenna system, it would be beneficial to be able to place into earth's orbit a relatively compact, lightweight and inexpensive antenna apparatus that can transmit/receive signals containing useful information from identifiable areas along the earth's surface, while reducing high beam-to-beam cross over loss. Additionally or alternatively, it would be advantageous to generate a plurality of transmitted or received signals in which one or more of the feed elements that are utilized to provide such signals are not dedicated to producing a particular beam or signal.